Easy,
Just go to your profile (from the upper tab) and then, click on "Forum Profile Information" then on the Signature's area, add this :
Banner 01[CENTER][URL=http://www.space-shuttle-mission.com]
[IMG]http://img353.imageshack.us/img353/6004/banner01my8.png[/img][/URL]
[/CENTER]
Banner 02[CENTER][URL=http://www.space-shuttle-mission.com]
[IMG]http://img509.imageshack.us/img509/4594/banner02wn4.png[/img][/URL]
[/CENTER]
Banner 03[CENTER][URL=http://www.space-shuttle-mission.com]
[IMG]http://img392.imageshack.us/img392/5993/banner03ih1.png[/img][/URL]
[/CENTER]
Banner 04[CENTER][URL=http://www.space-shuttle-mission.com]
[IMG]http://img360.imageshack.us/img360/1908/banner04yg5.png[/img][/URL]
[/CENTER]
Banner 05[CENTER][URL=http://www.space-shuttle-mission.com]
[IMG]http://img204.imageshack.us/img204/8020/banner05lj5.png[/img][/URL]
[/CENTER]
Official Banner 1[CENTER][URL=http://www.space-shuttle-mission.com]
[IMG]http://img339.imageshack.us/img339/6866/ssm2007forumsig01vb3.jpg[/img][/URL]
[/CENTER]
Official Banner 2[CENTER][URL=http://www.space-shuttle-mission.com]
[IMG]http://img339.imageshack.us/img339/3751/ssm2007forumsig02ab6.jpg[/img][/URL]
[/CENTER]
The URL of the images above has been uploaded on "
http://www.imageshack.us/" it's a free hosting image for forum. (you can of course take the one I've uploaded)